A Wnt/β-catenin signaling pathway is a signaling pathway which plays a critical role in the development, growth and homeostasis of vertebrate animals. An abnormal Wnt/β-catenin signaling pathway causes various diseases including cancer and osteoporosis. Activation of the Wnt/β-catenin signaling pathway is initiated from binding a receptor, Frizzled (Fz), and a co-receptor, lipoprotein receptor-related protein 5 and 6 (LRP 5/6), to a ligand, Wnt. A component protein, Dvl, of the Wnt/β-catenin signaling pathway present in the cytoplasm functions to transmit a signal generated from the binding of Wnt to Fz and LRP5/6 to a β-catenin destruction complex serving as a protein complex, and the signal transduction by Dvl serves to facilitate dissociation of the β-catenin destruction complex, thereby blocking polyubiquitination of a core factor, β-catenin, of the Wnt/β-catenin signaling pathway and thus destroying the β-catenin. Therefore, as the β-catenin in the cytoplasm is increased in amount, some of the β-catenin moves into cell nuclei, thereby facilitating expression of target genes having β-catenin transcriptional activities.
Dvl has three evolutionarily conserved functional domains. Among these functional domains, a Post Synaptic Density-95, discs-large and Zonula occludens-1 (PDZ) domain consists of approximately 90 bases. Some Dvl-associated proteins binding to Dvl function in such a PDZ domain regulate the Wnt/β-catenin signaling pathway.